1. Technical Field
The present disclosure relates to a device for detecting an output current of an inverter.
2. Description of the Related Art
An inverter is a typical power conversion device configured to receive and convert an alternating current (AC) power into a direct current (DC) power, and then convert again the converted DC power into AC power to control a power system.
The inverter is used in various forms, such as a fan, a pump, an elevator, a conveying device, a production line, and the like, across the industry.
The inverter includes a rectifier configured to rectify AC power, a capacitor of a DC-link, which is disposed between the rectifier and an inverter part and is configured to smooth the rectified AC power, and the inverter part.
A high potential side DCP and a low potential side DCN are provided at an output stage that is connected from the DC-link to the inverter part. A shunt resistor is connected to the low potential side DCN to detect an output current.
In detection by the shunt resistor, it is important to select a sampling timing. Since there are a dead time, a turn on time, a voltage signal stabilization time, and the like when a power switch is turned on or off due to a hardware structure of the inverter, sampling a current at such times may cause an increase of a measurement error. Therefore, the sampling of the current is performed not at a starting point of an effective vector but at a timing that is delayed by a predetermined time from the starting point thereof.
However, even though the sampling of the current is performed after being delayed by the predetermined time from the starting point of the effective vector, a current detection error may occur due to a hardware delay factor.